1. Field of the Invention
The present invention relates generally to the field of apparatus for binding a book and more particulary, to automatic bookbinding apparatus which utilize a binding tape comprised of a substrate which carries an adhesive.
2. Description of Related Art
Apparatus for binding books utilizing a binding tape carrying heat and/or pressure actuated adhesives are well known. For example, U.S. Pat. Nos. 3,928,119 and 3,911,517 disclose a bookbinding machine for binding a stack of sheets. The stack of sheets to be bound is first positioned on a movable plate and clamped between a pair of guides. A binding tape is positioned under the movable plate, below the spine of the book. The binding tape is supported intermediate two moveable heated platens and above a fixed heated platen.
Once the book is positioned, the moveable plate is moved away from the book and the book is translated downward, towards the binding strip. The spine of the book engages the binding strip and forces the strip down between the two moveable heated platen until the center of the strip contacts the fixed heated platen. The moveable heated platens are positioned apart a distance slightly greater than the width of the book so that the periphery of the binding tape will fold over the front and rear book covers.
The moveable platens are then forced together so as to seal the periphery of the binding strip to the front and back cover sheets using heat and pressure. The fixed heated platen functions to melt the central binding tape adhesive so as to wet the spine of the book (the edges of the sheet) with adhesive. The moveable platens are then retracted and the bound book is removed and permitted to cool.
A further bookbinding apparatus is disclosed in U.S. Pat. No. 3,531,358. The stack of sheets to be bound is gripped between a pair of opposing clamps. A binding tape having heat and pressure sensitive adhesive is positioned on top of a pair of heated moveable platens. The stack is then lowered on the binding tape so that molten adhesive contacts the edges of the sheets.
The pair of opposing platens then separate a distance slightly wider than the stack and the stack is forced down between the opposing platens thereby causing the peripheries of the binding tape to fold up against the front and back covers of the stack. The opposing platens are then forced against the stack so as to seal the tape to the covers. The platens are then opened so that the bound book may be removed.
A principal disadvantage of the bookbinding apparatus of the type previously discussed is that such apparatus are not capable of reliably binding relatively thin books. In each case, the folding of the binding tape is accomplished by exerting force through the stack or book itself. If the stack is thin, the stack does not have sufficient rigidity to fold the tape. This is especially true in the event a binding tape having relatively thick adhesives is used, since such tapes are somewhat rigid and do not fold as readily as other types of tapes.
The present invention overcomes the above-noted shortcoming of conventional bookbinding apparatus. Because the book is substantially supported throughout the binding sequence, books of narrow thickness can be reliably bound. This and other advantages of the subject invention will become apparent to those skilled in the art upon reading the following Best Mode of Carrying Out the Invention together with the drawings.